182 research outputs found
Electronic and Ionic Conductivities Enhancement of Zinc Anode for Flexible Printed Zinc-Air Battery
Zinc-air battery is considered a promising candidate for future energy applications due to its high energy density, safety and low cost. However, poor battery performance and low efficiency of zinc utilization, resulted from passivation effect of the zinc anode, is a major challenge. Thus, in this work, investigation of electronic and ionic conductivities enhancement of the zinc anode for flexible printed zinc-air battery has been carried out. The anode was made from a zinc-based ink, prepared from a mixture of zinc and zinc oxide particles. Carbon black, sodium silicate (Na2SiO3) and bismuth oxide (Bi2O3) were investigated for implementation on the anode. The results showed that performance of the battery increased when carbon black was introduced into the anode as the presence of carbon black improved electronic conductivity of the anode. Again, the battery performed better when Bi2O3 orNa2SiO3 was introduced due to the formation of solid electrolyte interface (SEI) on the anode. The SEI inhibits passivation of zinc active surfaces and provides effective electrolyte access. The battery with Bi2O3 provided the best performance. The highest performance was observed when Bi2O3 content reached 26wt.%. No significant improvement was observed whenBi2O3 concentration increased higher than 26 wt.%.Zinc-air battery is considered a promising candidate for future energy applications due to its high energy density, safety and low cost. However, poor battery performance and low efficiency of zinc utilization, resulted from passivation effect of the zinc anode, is a major challenge. Thus, in this work, investigation of electronic and ionic conductivities enhancement of the zinc anode for flexible printed zinc-air battery has been carried out. The anode was made from a zinc-based ink, prepared from a mixture of zinc and zinc oxide particles. Carbon black, sodium silicate (Na2SiO3) and bismuth oxide (Bi2O3) were investigated for implementation on the anode. The results showed that performance of the battery increased when carbon black was introduced into the anode as the presence of carbon black improved electronic conductivity of the anode. Again, the battery performed better when Bi2O3 or Na2SiO3 was introduced due to the formation of solid electrolyte interface (SEI) on the anode. The SEI inhibits passivation of zinc active surfaces and provides effective electrolyte access. The battery with Bi2O3 provided the best performance. The highest performance was observed when Bi2O3 content reached 26 wt.%. No significant improvement was observed when Bi2O3 concentration increased higher than 26 wt.%
Near-infrared photoluminescence from molecular crystals containing tellurium
We report the observation of near-infrared photoluminescence from
Te4(Ga2Cl7)2 and Te4(Al2Cl7)2 molecular crystals containing Te42+ polycations.
The experimental and theoretical results clearly revealed that Te42+ polycation
is one smart near-infrared emitter with characteristic emission peaks at 1252
and 1258 nm for Te4(Ga2Cl7)2 and Te4(Al2Cl7)2 crystals, respectively, resulting
from the intrinsic electronic transitions of Te42+. Furthermore, it was also
found that the emissions strongly depend on the excitation wavelengths for both
Te4(Ga2Cl7)2 and Te4(Al2Cl7)2 samples, most possibly owing to the co-existence
of other Te-related optically active centers. This research not only enriches
the species of luminescent charged p-block element polyhedra and deepens the
understanding of Te-related photophysical behaviors, but also may stimulate
efforts for designing novel material systems using such active centers. It is
also greatly expected that these sub-nanometer optically active species could
exist in other systems such as glasses, polymers, and bulk optical crystals,
and the stabilization of these centers in widely used hosts will pave the way
for their practical applications
Photoluminescence from Bi5(GaCl4)3 molecular crystal
Bi5(GaCl4)3 sample has been synthesized through the oxidation of Bi metal by
gallium chloride (GaCl3) salt. Powder X-ray diffraction as well as micro-Raman
scattering results revealed that, in addition to crystalline Bi5(GaCl4)3 in the
product, amorphous phase containing [GaCl4]- and [Ga2Cl7]- units also exist.
The thorough comparison of steady-state and time-resolved photoluminescent
behaviors between Bi5(GaCl4)3 product and Bi5(AlCl4)3 crystal leads us to
conclude that Bi53+ is the dominant emitter in the product, which gives rise to
the ultrabroad emission ranging from 1 to 2.7 micrometer. Detailed quantum
chemistry calculation helps us assign the observed excitations to some
electronic transitions of Bi53+ polycation, especially at shorter wavelengths.
It is believed that our work shown here not only is helpful to solve the
confusions on the luminescent origin of bismuth in other material systems, but
also serves to develop novel broadband tunable laser materials
Microwave-assisted polyol synthesis of copper nanocrystals without using additional protective agents
We report the synthesis of 2 nm copper nanocrystals (Cu NCs)via a microwave-assisted polyol method without using additional protective and reducing agents. The Cu NCs are oxidation resistant and exhibit photoluminescence and highly stableproperties in a colloidal dispersion
Ultra-broad near-infrared photoluminescence from crystalline (K-crypt)2Bi2 containing [Bi2]2- dimers
For the first time, we report that a single crystal of (K-crypt)2Bi2
containing [Bi2]2+ displays ultra-broad near-infrared photoluminescence (PL)
peaking at around 1190 nm and having a full width at the half maximum of 212
nm, stemming from the inherent electronic transitions of [Bi2]2+.The results
not only add to the number of charged Bi species with luminescence, but also
deepen the understanding of Bi-related near-infrared emission behavior and lead
to the reconsideration of the fundamentally important issue of Bi-related PL
mechanisms in some material systems such as bulk glasses, fibers, and
conventional optical crystals
A Novel Physical Approach for Cationic-Thiolate Protected Fluorescent Gold Nanoparticles
Knowledge on the synthesis of cationically charged fluorescent gold nanoparticles (Au NPs) is limited because the electrostatic repulsion between cationic ligands on the surface of NP hinders the formation of small Au NPs (usually less than ca. 2 nm) during nucleation in solvents. We herein propose a novel methodology for a synthesis of water-dispersible, cationic-thiolate protected fluorescent Au NPs by the sputtering of Au into liquid matrix containing thiolate ligands. By controlling mercaptan concentration the size and photophysical characteristics of Au NPs were directly controlled, resulting in near IR fluorescence with a 0.9% of absolute quantum yield. Cationically charged fluorescent metal NPs are promising, especially in biological fields, and this work provides a novel methodology towards the synthesis of a new series of functional metal NPs
One-pot preparation of cationic charged Pt nanoparticles by the autocatalytic hydrolysis of acetylthiocholine
We propose a novel synthetic approach for cationic charged platinum nanoparticles via the autocatalytic hydrolysis of acetylthiocholine. This method can be extended to the platinum group of metals
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